This invention relates to a cycle and, in particular, to a cycle wherein rotation of a drive wheel can be effected by the application of a force alternately to a pedal and to the or a saddle.
In a conventional bicycle, a drive wheel is adapted to be driven in rotation by means of a driven gear wheel, an endless chain and a driving gear wheel. The driving gear wheel is rotatable by means of two cranks having pedals rotatatably mounted thereon, the two cranks being mounted in opposition to one another. In use, a user may sit on a saddle of the bicycle and apply a force first to one pedal and then to the other, or the user may stand on the pedals and, by shifting his weight from one pedal to the other, effect rotation of the two cranks and thus of the driving gear wheel. A disadvantage of this arrangement is that the gear ratio between the driving gear wheel and the driven gear wheel, and thus the speed at which the bicycle can be propelled, is limited, because the maximum force which is applied to a pedal of the bicycle in use is generally somewhat less than the weight of the user. A further disadvantage is that the bicycle may be unsuitable for use by a disabled person, because two limbs are needed to operate the pedalling mechanism.
UK Patent Specification No. 234,363 describes a driving mechanism for a vehicle in which a pedal and a saddle are pivotally vertically movable and are interconnected by a pulley mechanism so that, in use, the rider's weight is applied alternately to the pedal and the saddle to effect periodic vertical movement of the saddle. The saddle is coupled via a pulley and spring mechanism to an axle of a drive wheel, which is also provided with a pawl and rachet mechanism to ensure that rotation of the axle occurs in one direction only. The drive wheel is driven only during upward movement of the saddle, which may limit the velocity which can be achieved, as well as, possibly, adversely affecting maneuverability. Furthermore, the various pulley and spring arrangements are complex and may be subject to early wear and damage.
UK Patent Specification No. 402,369 discloses a vehicle having a frame, a crossbar which is pivoted to the frame and has a saddle fixed thereto, a lever member pivoted to the frame, foot rests fixed to the lever member and crank means, similar to those of the conventional bicycle described above, rotatably mounted on the frame for transmitting rotation to a drive wheel of the vehicle. Each of the crossbar and the lever member is coupled to the crank means via a respective force transmission member which is vertically reciprocal with rotation of the crank means. Thus, rotation of the crank means is effected by the application of a substantially vertical force alternately to the saddle and the foot rests. This vehicle has a larger number of pivot points, which may detract from the mechanical strength of the vehicle and reduced the efficiency with which the weight of the user can be applied.
UK Patent Specification No. 424,566 discloses a similar arrangement in which the crank means is provided with a pair of off-set throws, one of which is linked to a lever member vertically pivoted to the frame and the other of which is linked to the foot reats, which are horizontally pivoted to the frane. Vertical movement of the lever member can either be effected by the application of the rider's weight to the saddle or by the restoring action of a tension spring. In addition to the disadvantages referred to above, the rider's full weight cannot be applied to the foot rests.
UK Patent Specification No. 457,307 discloses a bicycle in which both the saddle and a pedal crank axle are horizontally and vertically pivotal relative to the frame. The saddle is linked to the pedal crank via a force transmission member so as to effect rotation of the pedal crank in response to the application of the user's weight alternately to the saddle and to a pedal or pedals. However, movement of the saddle occurs both vertically and horizontally, leading to a reduction of efficiency. Also, the pedal crank may be limited in size, because it is not supported directly by the frame. The very large number of pivot points may render this device particularly vulnerable to mechanical stress.
UK Patent Specification No. 626,900 discloses a tricycle having two rear wheels with a common axle, in which a saddle is pivotable vertically with respect to the rear axle and a crank means, formed integrally with the rear axle, is rotatable in response to vertical movement of the saddle. Movement of the saddle in the upwards direction is effected by means of a pair of levers, each of which is provided at one end with a foot rest, pivoted at an intermediate point to a frame of the tricycle, and linked at its other end to the saddle via a link member. This arrangement suffers from a number of disadvantages. In particular, it is not possible for gearing to be provided, so that the velocities which can be achieved may be limited.
It is an object of the present invention to enable the provision of a cycle, for example, a bicycle, whereby the above disadvantages may be overcome, or at least mitigated.